Electric discharge apparatus



Feb. 2, 1937. J. w. DAWSQN 2,069,734

ELECTRIC DI SCHARGE APPARATUS Original Filed June 29, 1933 5 Sheets-Sheet 1 WITNESSES: INVENTOR q i1? John m Dawson. m BY Feb. 2, 1937. J w, DAWSON 2,069,734

ELECTRIC DISCHARGE APPARATUS Original Filed June 29, 1933 5 Sheets-Sheet 2 WITNESSES:

INVENTOR J Lib/1r:3 Y W Dawso Feb. 2, 1937. J. w. bAwsoN 2,069,734

ELECTRIC DISCHARGE APPARATUS Original Filed June 29, 1933 5 Sheets-Shet 3 Fig. 9

WITNESSES: INVENTOR John W Dawson.

Feb. 2, 1937. J. w. DAWSON 2,059,734

' {ELECTRIC DISCHARGE APPARATUS Original. Filed June 29, 1933 5 Sheets-Sheet 4 F'I' JO,

25/ an I63 1' 259 I i= 2Q? as 253 5:5 269 255 2 51- I67 I85 mg F17. II. /32 325 WITNESSES: INVENTOR John W. Dawson.

Feb. 2, 1937.

J. W. DAWSON ELECTRIC DISCHARGE APPARATUS Original Filed June 29, 1 933 5 Sheets-Sheet 5 INVENTOR John W Dawson.

I WITNESSES; vim Q 7 ATTORNE Patented Feb. 2, 1937 ELECTRIC DISCHARGE APPARATUS John W. Dawson, Wilkinsburg, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Original application June 29, 1933, Serial No.

678,237. Divided and this application September 26, 1935, Serial No. 42,174

20 .Claims.

My invention relates to electric discharge apparatus and it has particular relation to apparatus of the type utllizedin power supply systems.

The present application is a division of my copending application Serial No. 678,237 filed June 29, 1933, and assigned to the Westinghouse Electric 8: Manufacturing Company. In their more restricted scope, the parent application and the present application are directed to improvements m of the system shown and described in my Patent No. 1,928,812, died December 19, 1930, granted October 3, 1933, and assigned to the Westinghouse Electric & Manufacturing Company, reissue 'ap-' plied for January 11, 1934, Serial No. 706,303. For 15 this reason the objects accomplished by my present invention can perhaps be most adequately explained with reference to the patent.

In my aforesaid Patent No. 1,928,812, a power supply system for vibratory apparatus, such as a mechanical shaker screen, for example, is shown and described. The element that is to be vibrated is coupled to an eiectromagnet that is intermittently energized and deenergized. When the magnet is so energized and deenergized, it sets the vibrating element in vibration. The electromagnet is energized from a suitable power source .through a plurality of electric discharge devices of the asymmetric type.

The power source is of the alternating current type and, in practice, has the usual commercial frequency of 60 cycles per second. The frequency at which it is desired to motivate the vibrating element is, in general, of the order of or cycles per second, and the electric discharge de- 8 vices are utilized for the .purpose of controlling the supply of intermitting current to the magnet.

The electric discharge devices of the type preferably utilized in the system described in the above-mentioned patent each have an anode, a cathode and a control electrode, all immersed in a gaseous medium at a low pressure. Each of the devices has only an energized condition and a deenergized condition and is capable only of abrupt transition from one condition to the other. 5 The particular condition of the device at any given time depends on the potential applied between the anode and the cathode (which will be herein designated as the principal potential) and on the potential impressed between the control electrode and the cathode (which will be herein designated as the control potential). When the principal potential is positive (i. e., the anode is positive relative to the cathode) and oi proper magnitude and when the control potential is of proper mag- 55 nitude relative to the principal potential, the" electric discharge device is energized. It thereafter remains in its energized condition regardless of the variations in magnitude of the control potential until the principal potential is reduced to a value substantially below the ionization potential of the gas in which the electrodes are immersed.

Whenthe principal potential impressed on the electric discharge device is an alternating potential, the device remains deenergized as long as the control potential remains below a predetermined value, (which I shall herein designate as the limiting control potential). If the control potential at any time during the interval during which the principal potential is positive rises above the limiting control potential, the electric discharge device becomes energized and remains energized during the remaining portion of the positive halt cycle of principal potential and it becomes deenergized only when the principal potential is sufllciently reduced.

In the system described in my aforesaid patent, the electric discharge devices are supplied with commercial alternating potential. They are, therefore, even when once energized, deenergized with a periodicity dependent on the frequency of the source and with this periodicity are subject to the control of the control potential. The control potential is varied in a manner corresponding to the frequency at which it is desired to energize the vibrating element of the shaker.

When the control potential impressed on the electric discharge devices is of proper magnitude the devices are alternately energized, as positive principal potential is impressed on their electrodes, and the load is supplied with current. Subsequently, the control potential impressed on the electric discharge devices is so varied that they are both deenergized, in which case, the electromagnet of the vibrator system should also be deenergized. However, it willbe noted that during the energizing period a magnetic flux of considerable magnitude is built up in the electromagnet. As the flux collapses, a back potential appears across the terminals of the electromagnet, and

this potential would tend, in the absence of proper suppressing apparatus, to maintain the last of the electric discharge devices to be energized in spite of the fact that the control potential and the principal potential supplied by the power source is at a value corresponding to a deenergized condition. Essentially what happens in such case is that the back potential of the load is greater than the forward potential of the source and in consequence thereof the principal potential impressed on the electric discharge device remains positive.

To suppress this condition, I have, in accordance with the above-mentioned patent, provided a dissipating-network which is asymmetrically conductive. The net work is connected across the windings of the electromagnet in such manner that it is non-conductive to the current flowing into the windings of the electromagnet when the latter is being energized, but is conductive to a current transmitted under the back-electromotive force generated by the collapse of the flux in the electromagnet. The energy stored in the electromagnet is thus dissipated in the network and prevents the electric discharge devices from remaining energized when they should be deenergized.

It is to be noted that the use of the dissipating network in the system described in my earlier patent results in the loss of a considerable portion of the energy supplied to the load. The operation of systems in which the currents transmitted through the load are comparatively high therefore, involves considerable expense. In addition I have found that suppressing networks of the type utilized in the systems described in my earlier patent do not always operate emciently to suppress the back electro-motive force and do not suppress this electro-motive force at the high rate that is necessary for proper operation.

It is, accordingly, an object of my invention to provide a mechanism for intermittently supplying power to a load of the type having the property of storing a portion of the energy supplied thereto, without sufiering a large incidental power loss from. the necessary intermittent dissipation of the energy stored in the load.

Another object of my invention is to provide apparatus incorporating electric discharge devices for supplying power intermittently to a load of the type having the property of storing a portion of the energy supplied thereto, without entailing-the loss of the energy stored in the load.

Still another object of my invention is to provide apparatus incorporating electric discharge devices for supplying alternating current power to a load of the type having the property of storing a portion of the energy supplied thereto, wherein the energy stored in the load shall be dissipated at at least as high a rate as the rate at which it is stored.

A further object of my invention is to provide highly eflicient apparatus of the type incorporating electric discharge devices for intermittently supplying power to a load of the type having the property of storing a portion of the energy r.upplied thereto.

A still further object of my invention is to provide highly efficient apparatus for converting power pulsating at a given frequency into power pulsating at a predetermined difierent frequency.

A more specific object of my invention is to provide an eilicient power supply system of the type incorporating electric discharge devices for intermittently supplying current to a load of the inductive type.

Another specific object of my invention is to provide an eflicient power supply system without moving mechanical parts for supplying power at a predetermined periodicity to a load of the type having the property of storing a portion of the energy supplied thereto.

An incidental object of my invention is to provide a control circuit for a discharge device which shall operate to provide control potential 01 9.

given magnitude at times at certain points in the periods of principal potential supplied to the discharge device and at times at other points in the periods of principal potential.

More concisely stated, it is an object of my invention to provide apparatus that shall operate efilciently to convert power of one frequency into power of a smaller frequency.

According to my invention, I provide a power supply system of the type incorporating electric discharge devices in which the control potential of the electric discharge devices is so varied that energy is supplied to the load for a predetermined interval of time, and a portion of the energy is stored in the load. After this interval of time the relationship of the load and the power In accordance with one embodiment of my in- 'vention, the control potential for the electric discharge devices is varied by a system incorporating a plurality of current interrupting contacts that are properly motivated. In accordance with another embodiment of my invention. l

the condition of the electric discharge devices is controlled by shifting the phase of the control potential at the desired periodicity. According to one modification of this embodiment of my invention,.the phase shift is attained by the rota- 1 tion of a suitable movable contactor or commutator in and out of engagement with cooperating flxed contact elements, and in accordance with another modification of this embodiment, the phase shift is attained by utilizing a suitable non-mechanical timing circuit. As will be explained hereinafter, my invention is applicable both to power supply systems incorporating electric discharge devices of the type having controi'electrodes, and to power supply systems of the type incorporating electric discharge devices having starting or ignition electrodes, such as the Ignitron tube, for example, The latter discharge devices will be explained more in detail hereinafter in connection with Figs. 3 and 4.

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of specific embodiments, when read in connection with the accompanying drawings; in which Figure 1 is a diagrammatic view showing an embodiment of my invention utilizing hot-cathode, electric discharge devices;

Figs. 2, 2A and 2B together constitute a plot illustrating the operation of the system shown in Fig. 1;

Fig. 3 is a diagrammatic view showing a modification of my invention in which the electric discharge devices are of the type incorporating starting or make-alive electrodes;

Fig. 4 is a diagrammatic view showing a modification of the system in which the electric discharge devices are of the type incorporating starting or make-alive electrodes;

Fig. 5 is a diagrammatic view showing a modificatlon of my invention in which the desired result is attained by phase shift of the control potential or of the Starting current;

Fig. 6 is a vector diagram illustrating one feature of the'operation of the system shown in Fig. 5;

Fig. '7 is a graph corresponding to Fig. 6;

Fig. 8 is a vector diagram illustrating another feaure of the operation of the system shown in Fig.

Fig. 9 is a graph corresponding to Fig. 8;

Fig. 10 is a diagrammatic view showing a further modification of my invention in which moving mechanical parts are not utilized;

Fig. 11 is a vector diagram illustrating a feature of the operation .of the system shown in Fig. 10;

Fig. 12 is a graph illustrating the operation of the system shown in Fig. 10; and,

Fig. 13 is a diagrammatic view showing an embodiment of my invention in which alternating power of one frequency is converted into alternating power of a second frequency.

The apparatus shown in Fig. 1 comprises a plurality of power supply bus lines which are supplied with alternating current from a power source (not shown) and to which the terminals of the primary 3 of a transformer 5 are connected. The secondary of the transformer 5 is provided with a section 9 equipped with a plurality of terminal taps H and i3 and an intermediate tap l5. The terminal taps H and I3 of the section 9 of the secondary I are connected directly to the anodes l1 and IQ of a plurality of electric discharge devices 2| and 23. The cathodes 25 and 21 of the electric discharge devices 2| and 23 are of the so-called hot-cathode type, as shown, and are connected to each other at a junction point 29. The intermediate tap |5 of the secondary section 9 is connected to the junction point 29 of the cathodes through an inductive, power-consuming load 3| that is to be supplied with power from the source I through the electric discharge devices 2| and 23.

The electric discharge devices 2| and 23 are preferably of the grid-glow type utilized in the system described in my aforesaid Patent No. 1,928,812. I have found that for many purposes the Westinghouse grid-glow tube ICU-628 is of considerable utility in the present connection. However, if the requirements of the load circuit permit a smaller tube, the Westinghouse gridglow tubes KU627 or KU610, for example, may be utilized.

In the customary practice of my invention the principal potential has a peak value that is of the order of volts and for the particular electric discharge devices that are preferably utilized, the corresponding limiting control potential is of the order of --2 volts. When the control potential is raised to a value above (or more positive than) this limiting value during the interval during which positive principal potential is supplied, the electric discharge device 2| or 23 for which this condition occurs is energized and remains energized during the remainder of the positive half cycle of principal potential.

The condition of the electric discharge devices 2| and 23 in the system shown in Fig. 1 is controlled from a plurality of rotating contactors or commutators 33 and 35 that are rotated by a synchronous motor 31 energized from the bus lines I of the power supply source and, therefore, energized in synchronism with the source. Each of the commutators 33 and 35 is, respectively,

equipped with an inner conducting ring 33 and 4| and with an outer conducting ring 43 and 45 provided with a plurality ofv specially positioned insulating inserts 41 and 49 and 5|, 53 and 55. A plurality of brushes 51 and 59, connected to the negative terminal of an auxiliary power source 6| that may be preferably a battery of voltaic cells, engage the inner rings 33 and 4|; while a plurality of brushes 63 and 65, connected to the control electrodes 61 and 69 of the electric discharge devices 2| and 23, respectively. through suitable grid resistors II and I3, engage the outer rings 43 and 45. The positive terminal of the battery BI is connected to the junction point 23 of the cathodes 25 and 21.

When the brushes 63 and 65, engaging the outer rings 43 and 45, are in contact with the conducting portions of the rings, the negative terminal of the battery 6 i, to which the inner brushes 51 and 59 are connected, is connected through the rings and brushes to the control electrodes 51 and 53 of the electric discharge devices 2| and 23. This potential is of such magnitude that the control potential is more negative than the limiting control potential for the electric discharge devices, and the electric discharge devices remain in their deenergized condition. On the other hand, when either of the outer brushes 83 or 65 is engaged by an insulating insert 41 or 49 or 5|, 53 or 55,-the corresponding control electrode 51 or 69 is disconnected from the auxiliary power source 5|, and its potential is raised substantially to the potential of the corresponding anode I! or l9 to which it is connected through another resistor 15 or 11 of suitable character. When the control electrode 61 or 69 of eitherelectric discharge device 2| or 23 is thus raised to the anode potential, at a time when the anode potential is positive, the electric discharge device becomes energized and transmits current through-the load 3|.

The insulating segments 41 and 43, and 5|, 53 and 55 and the outer brushes 63 and 65 are so dispowd relative to each other that the following series of conditions existin the electric discharge devices 2| and 23.

(1) The electric discharge devices 2| and 23 are alternately energized by interrupting their normally existent negative control potential connections, substantially at the beginnings of each of a plurality of successive half-cycles of positive potential, until a full current of predetermined magnitude is built up in the load 3|, as will be explained in connection with Figs. 2, 2A and 2B.

(2) This full-current condition is necessarily attained during a half-cycle in which positive principal potential is supplied to one of the electric discharge devices (e. g. the device 2|) and negative principal potential is supplied to the other discharge device (e. g. the device 23). At the beginning of the next half-cycle of princi pal potential, when the principal potential supplied to the last-mentioned discharge device 23 becomes positive and the principal potential supplied to the former discharge device 2| becomes negative, the control potential supplied to the discharge device 23 by the battery 6| is not interrupted, as heretofore at the beginnings of each half-cycle ofthe supply voltage, but remains negative, and hence the discharge device 23 does not become energized.

(3) By reason of the non-energization of the electric discharge device 23, the discharge is not transferred from the formerly energized electric discharge device 2|, and the latter, in spite of the fact that its principal potential is now negative, remains in its energized condition and draws current from the load, returning power to the powersupply line, during nearly all of one half-cycle.

(4) Nearly, but not quite, at the end of the last-mentioned half-cycle of principal potential, the second discharge device 23 (which now has positive principal potential impressed thereon) is energized by the engagement of its corresponding outer brush 65 with an insulating segment such as 49, resulting in the removal of the negative potential from its control electrode 69. (5) The latter electric discharge device 23, therefore, becomes energized and shunts out the former electric discharge device 2|, extinguishing the device 2|, and for the remainder of its positive half-cycle of principal potential, the device 23 feeds current into the load 3|.

(6) However, since the principal potential on the discharge device 23, as supplied by the secondary of the transformer, soon becomes negative, this discharge device 23 also begins to draw current from the load and thus further decreases the current passing through the load, until nearly at the end of its half-cycle of negative principal potential, when the former device 2| is again energized and repeats the performance just described for the device 23.

. (7) This procedure is repeated until the current in the load is substantially zero.

(8) At thisiuncture, or at a predetermined interval later, one of the electric discharge devices 2| is again energized substantially at-the beginning of its positive half cycle of principal potential and the load 3| is again supplied with current from the power source.

It is to be noted that in accordance with vthe above enumerated steps the load 3| is first supplied with power under the positive electromotive force of the power source and subsequently it gives up its stored energy .when the electromotive force of the power source is negative. Since, in an ordinary power supply system, the positive half wave of output potential is equal in magnitude to the negative half wave of output potential, the load 3| may be deenergized at a rate which is at least as high as the rate at which it is energized. That is to say, since the force supplying power to the load is of the same magnitude as the force withdrawing usefuipower from the load, to say nothing of the work being done by or in the load, the demagnetizing operation may take place at as great a rate as the magnetizing operation, or even at a greater rate, and the diiiiculty which arises in the systems constructed in accordance with my earlier ap plication does not exist.

It is seen that, in accordance with the above procedure, the load 3| is supplied intermittently with power and intermittently feeds back power to the power source. In this manner the exciting coil of a vibrating system, such as a shaker screen, may be intermittently energized at a high efliciency.

The proper spacing of the insulating segments.

on the outer rings 43 and 45 is shown in detail in Fig. 1. The rings 43 and 45 are rotated in a counter-clockwise direction. The cycle of operations may be regarded as beginning with the engagement of the upper insulating segment ll of the left hand ring 43 with the brush 65 connected to the control electrode 33 of the righthand electric discharge device 23. The engagement of the two contact elements I and 65 takes place at the beginning of the positive half cycle of principal potentialapplied to the right hand electric discharge device 23. Current is thereupon supplied through the electric discharge device 23 to the load 3|.

The next element to be engaged by a brush is the lower insulating insert 41 of the right-hand outer ring 43 which is engaged by the brush 63 connected to the control electrode 61 of the left hand electric discharge device 2|. The former insulating insert 5| and the latter insulating segment 4'! are so spaced with reference to each other and to the corresponding brushes 65 and 63 that the engagement of the brush 63 with the insert 41 takes place at the beginning of the half cycle of positive principal potential applied to the left-hand electric discharge device 2| and consequently at the beginning of the negative half cycle of principal potential applied to the right hand electric discharge device 23. Thelefthand electric discharge device 2| is "therefore, energized while the right-hand electric discharge device 23 is deenergized, and the supply of current to the load 3| is continued.

At the beginning of the next successive half cycle of potential the brush 65 that is connected to the control electrode 69 of the right-hand electric discharge device 23 is engaged by the insulating insert 53 of the left-hand outer ring 45. The right-hand electric discharge device 23 is, therefore, .reenergized while the left hand device 2| is deenergized, and the current which is transmitted to the load 3| is further increased.

At the beginning of the next subsequent half cycle of principal potential, neither of the brushes 63 or 65 is engaged by an insulating segment, and the inductive load 3| now supplies energy to the power source through the electric discharge device 23 that was last energized. This condition continues until nearly the end of that half cycle of principal potential. At this point, the remaining insulating segment 49 of the right-hand outer 7 ring 43 is engaged by the brush 63 which is connected to the control electrode 61 of the left-hand electric discharge device 2 l, and the latter device is energized. When it is so energized, the left hand device 2| shunts out the other electric discharge device 23 and the latter device is deenergized. The left hand electric discharge device 2| now continues in its energizedcondition during the remainder of the half cycle in which it has been energized, and during the subsequent half cycle in spite of the fact that the principal potential supplied by the power source takes on a negative polarity during the latter half cycle. The load 3| supplies power through the device 2| to the power source during the latter half cycle of principal potential. When the end of this half cycle is approached, the brush 65 which is connected to the control electrode 69 of the righthand electric discharge device 23 is connected to the remaining insulating segment 55 of the lefthand outer ring, and this electric discharge device ls energized, nearly at the end of its positive half cycle of principal potential, and shunts out the other electric discharge device 2|. It supplies current to the load for the short interval remaining of the positive half cycle of principal potential applied to it and then draws current from the load 3|. At this point the current in the load 3| is reduced substantially to zero and the above-described series of steps is repeated.

The operation of the system is illustrated in detail in Figs. 2, 2A.and 2B. The principal potential applied to the right-hand electric discharge device 23 is shown as a full-line sine curve I! having a plurality 01 positive half waves 8 l, 83 an'dtE Q plotted against time. The positivehali waves of principal botefitial applied to the leit hand-electrlc :dischhrgefdevice 2] are shown as-broken-line ghelt-wevejsine curves 81,89 and It. )The current supplied the. load'3| is shown as a: iuliline curve 93 that extends aibove the curves.- representin'g theprincipal'potentials supplied to theelec- 'tric discharge devices 2i .and 23. 4 The outerirings 4'3 and of the commutatorsjlend Stare fplotted' aevemg mh Figs. 23 and--24 respectively,-

' and in the plot the insulatins inserts-.11 H, II, 53

: End flhre'shown, withreierence-tothe halt waves 1m: to e e i i first upper; insulating segment" of the left-hand .beco

'and 2B.-

" or principalfpotentiel', at the points .st which they Qar e engeged by the. Brushes l8 and N.

deter contictor ring 48 is shownin a, position corp esnbn i flo the sin soihe si i e lf f cycle of principal potential, 1 At the aterting-point represented in Figs. 2 end 2A, theinsulatins 8 8- .men't' l l tisfleng aged hyQthebx-ush in Fig. .1. The electricfdischarge device 2;. to which the positive riiicinell ngtfehtiel is applied at, this point and supplies currenttotheioad building up in opposition to themn t team {by theshsded area, 8 under the curve lt -The insulating insert -41 m}! ir'ii'm'ni'glor .{the positive halt wave 01 or.

"principal potential which is supplied to the other lead We??? i i ins i 's llm w 1 ;-I"18'.;f2 h y i s tw v -x p l potential I": insulating insert 53 on, the. left handn e' f l el o I so? thefpeginfnin if'jthenext haiiwsvels oi Principe! potential,

charge devices zrefzsjis'euemiz d by Neriation henna-g the electric disorinte'rrunt'ion or theicontrol potential, which is normally strongly negetive; byreason oi thelcom nection of the bettry--. -l"- However, therighthand electric idischergeiidevicq fl which was energized at the beginning olthe half cycle 83,

' remains in its energizdcondition odd continues to draw current iromthc load, ving its principal voltage from the coilnpsing -magntic lines-oi, force in the inductiveinpedance or the load. This condition isrepresenfigid; the jshsded. nree 89 under thejcurrent'curve '3: By reason oftheiect that the maidv s! minnlistfenergy oi source}. besides consuming ener y withinitself;

the current passing' throughihe mm isi weasedand itis so shown'in4Fig. 2 g Near the endoi thehalt; cycle 89 of .positiveprincipelgnotentiel applied'to the leit-handgelectric (nacho- 786. device Illihe' brnsh' on the righthend-outer ring 43 in Fig.'1 isenga;ged hy the insulating insert 4'9. The leitfhand eiectricldischerge device It is therefore-energized and for a short interval or time currenti fsuhhneq through it hi the load} 1-.

This'lcondition results inen'increese inzthe our, 4 rent transmitted through the load asia illustrated" .b'y the riseoi the-current curve 3! in: the region renewin .the'point at which the left-hand el c tric' discfi e device is energized; However, the principal notentielappliedio the nowenergized i; electric discharge devicell from the source soon cycle end :the

-.repe'alted. i 7 g I It isto'be noted thatthesynchronous mutant hn j n act'fl sj 1 -l'iz. 1 .s tly ng'agesjitscorresponding brush: 8! at electric'dis'clijerg'eigdev'ice1|, as' shown in Figs.- '2 c point, th electric discharge e vice 2I isneig'hzdendgurrentis mppuecw the ring ellisenseged, and-current is sup-s I nted by the shaded becomes negative 'and energy is supplied to the .power source by the load 3|;- The current in the load. is; therefore; further decreased.

-ruhau the right-hind electric discharge de- -.vice- 23 in Fig. l is energized sfibstentiaiily atwthe end of its positive 'hali cycle b! positive princi-' palpotentiaLend for -'a; short interve'l oi time the current in-the iced increases; as shown by therise in the current curve-83 'in' Fig. 2. j-However, the :principal-potential applied to the right-hand e1ectric discharge device 23 from the source "soon be .comes-negative end the cuflnt'pdssing through lithe load ialls to'substantially'zero veiue'ashown o -in the shaded" ores. illi undergthecurifent curve 93; After this conditionoccurs the right-hand electric discharge device 23 is'ogain energized'substantially at- 'the beginning or its ppsitiv h ir abovedescrihe'dseri step is in the-system shown in Figfl'is-oi'th type'incob porating am externally-excited new: iwhien s. 'motor of this type is synchron'i edfwith e- 'power source the' engular position of hnyfioint' on the rotor-bears a fixed relationship-to the waves of alternating potentisl ithet erem nee to the armature; Consequently.- ii the 'comxnutstors 33 and5l5 ere bropcrly position'do'n theroto'r shalt, the system will always start'and operatejwith'the .brushes' u and N-enx'aging-the msehts q, s, 5|, j] and" at instants corresponding points 1: which. itisdes'ired "the bruhnessheinde gege'the'iw I 'i'or'proper opera" "tionif mm; s m mvenuonn applied to vice otth'is general; h' vflporlk able reconstructing c'sthodefioi 'e as mercury or tin-Fc'nd an anode to cooperate system incorporating 'electric ,devices-1o: 'nnd ili oi the' 'ini'ake-alive typejsuch 88 :th Jgnitron' electric dischsr'gedewith the cathode? conductingin'eke nected to the secondary I of the transformer .5 in.

the some manner as the corresponding electric discharge devices II and 23 are connected in the lljeot-the'eleotric-dischalrge devices "Bend I05 areg'respectiv'elyfconnectedto the terminal, taps H and iii or the-kecohdhryfl, while the cathodes IN and HI oi theelcctric disohztrge devices are. connected to eech other'end their'common junction point}! is connected'to the intermediate tan iiofthojeccndarythrough the load 31'. v 4

socidted with thymak itlive electrodes us and I lliofthe-elect'ricdischargefdevices I!) end I05. Theconimutdtoriijlllmnd' I I} might: he, so. to spook, regardedhs theelectrical negetivesjot the, commutatora fl 'and '35 associated with the control electrodes l1 and'ilotithe' electric discharge devices "and 23 or the system shown-in. li"igr.' 1. v

mtm rehuents in commutator; ore co'nducting rings 39 and 4| as in the former system. However, the outer elements comprise insulating rings I23 and I25 in which are inserted a plurality of conducting inserts I21 and I29 and I31, I33 and I35 which are connected to the inner rings 39 and 4|, respectively. The conducting inserts I21, I29,-I3I, I33 and I35 are located at points in the rings I23 and I25 that correspond to the positions of the insulating inserts 41, 49, 5|, 53 and 55 in the outer rings 43 and 45 of the system shown in Fig. 1. The conducting inserts I 21 and I29 are conductively connected to the corresponding inner ring 39 while the conducting inserts I3I, I33 and I35 are connected to the corresponding inner ring 4| The brushes 51 and 59 that are in engagement with the inner conducting rings 39 and 4| are connected to the respective anodes I01 and I 09 of the electric discharge devices I03 and I05, while the brushes 63 and 65 that are in engagement with the outer rings I23 and I25 are connected to the make-alive electrodes H9 and IN of the respective electric discharge devices through suitable current limiting resistors I31- and I39. When a brush 63 or 65, connected to a make-alive electrode H9 or I2I, engages a conducting insert I21 or I29, or I3I, I33 or I35, the make-alive electrode is connected to one of the terminals of the power source and current is transmitted through the electrode and through the corresponding cathode III or II3. If the current is of proper magnitude and polarity, the corresponding electric discharge device I03 or I05 is energized or caused to become conducting.

For the present purpose let it be assumed that, at the instant corresponding to the position of the elements as shown in Fig. 3, the right-hand terminal I3 of the secondary I of the transformer 5 is positive relative to the intermediate tap I5 and the left-hand terminal II is negative relative to the intermediate tap. At this instant the brush 65 connected to the make-alive electrode I 2| of the right-hand electric discharge device I05 is engaged by the conducting segment HI and current is transmitted through the make-alive electrode in a proper direction for ignition. The right-hand electric discharge device I05 having at this time the proper principal potential applied thereto is, therefore, energized when the makealive current attains the starting value, and current is supplied to the load 3|.

Since the circuit shown in Fig. 3 involves a feature of considerable importance, it may be well to digress here to explain this feature. It is to be noted that each of the make-alive circuits is connected at one of its terminals to the anode I01 or I09 of its associated electric discharge device I03 or I05, and at the other terminal it is connected to the cathode III or I I3 of the associated electric discharge device- Consequently, when one of the electric discharge devices, I05 for example, is energized, the corresponding makealive network is shunted out, and the current which was originally transmitted from the then positive terminal I3 of the secondary I through the contact elements 59, 4|, III and 85, thence through the make-alive electrode I 2I of the right-hand electric discharge device I05, the cathode H3 01 this device and the load 3|, to the intermediate tap I5 01 the secondary, is now transmitted between the principal electrodes I09 and H3 or the right-hand electric discharge device I 05, and thence through the load 3I to the intermediate terminal l5 of the secondary. The current supplied to the make-alive electrode I2 is, therefore, necessarily decreased after the elec tric discharge device is energized, and hence th current that must be interrupted at the contacto In, by the disengagement of the conducting in sert I3I from the brush 65 which is connecte to the make-alive electrode I2I, is comparativel small. In this manner, sparking between th contacts and the brushes, which would deleteri ously afiect these elements, is suppressed, an the magnitude of the make-alive current drawl by the high resistance starting circuit is main tained at a minimum. It is to be noted that th latter advantage is of considerable importanc since, in make-alive electric discharge device. of this type, the starting current may have 1 magnitude as great as 5 or 10 amperes. By utiliz ing the system shown in Fig. 3 with the featur' described hereinabove, not only are the contac members of the commutators H5 and II! pro tected from disintegration, but the starting elec trodes are prevented from becoming excessivel; heated, and considerable power is saved.

To revert now to the essential features of th system shown in Fig. 3, the current transmittm between the principal electrodes I09 and H3 0 the right-hand electric discharge device I05, whei once initiated, continues during the remaindei oi the positive half cycle of principal potentia impressed on this device. Since the potentia drop between the anode I09 and the cathode III of the electric discharge device I05 is comparatively small when the device is energized, tht cathode H3 is, during this interval, at substantially the potential of the anode I 09 and consequently at the potential of the right-ham terminus I3 of the secondary I.

At the beginning of the subsequent half cycle of principal potential, a conducting insert I21 it the right-hand ring I23 is engaged with the brush 53 which is connected to the left-hand starting electrode H9. The difi'erence of potential between the starting electrode I I9 and it: corresponding cathode III is now substantially equivalent to the potential difference between thr two terminal'taps II and I3 of the secondary l or the transformer 5. When the circuit through the starting electrode I I9 is completed by the engagement oi the conducting insert I21 and the brush 63 connected to the starting electrode, sufficient current is transmitted through the starting electrode to energize the left-hand electric discharge device I03, and when it is energized. current is transmitted through it and to the load 3|.

The above series of steps are repeated until suitable current is built up in the load 3|. After this condition is attained, the inserts I29 and I35} being properly positioned in the rings I23 and I25, engage the brushes 63 and 65 at instants corresponding to the latter portions of the positive half cycles of principal potential, as previously explained and the electric discharge devices I03 and I05 are so energized as to draw current from the load 3i and supply it to the power source in the manner explained with regard to the system shown in Fig. 1.

The system shown in Fig 4 is largely similar to the system shown in Fig. 3. Experiments with make-alive electric discharge devices have demonstrated that their operation is most satisfactory when current is transmitted through the starting electrode only in a direction proper to ignition, and is not transmitted in the opposite direction. For this reason, the preferred prac- $106 has been to energize the make-alive circuit of an electric discharge device through an-asymmetric electric discharge device preferably of the hot cathode grid-glow type.

A system in which this procedureis followed is shown in Fig. 4. In this system, the makealive electric discharge devices I 03 and I05 are connected to the secondary 1 of the transformer 5 and to the load 3I in the same manner as the corresponding devices are connected in the system shown in Fig. 3. However, a plurality of hotcathode electric discharge devices I49 and I5I are provided, having principal electrodes I4I, I43 and I45, I41 which are connected in series with the respective make-alive electrodes I I9 and HI, the corresponding cathodes III and H3 of the electric discharge devices I03 and I05, and the corresponding terminals II .and I3 of the secondary 1. The hot-cathode electric discharge devices I49 and I5I have control electrodes I53 and I55 which are supplied with potential from a system of commutators 33 and 35 and a battery SI that are identical in structure and arrangement to the corresponding elements of the sys tem shown in Fig. l. The hot-cathode electric discharge devices I49 and I5I are energized in the same sequence as the devices 2| and 23 of the system shown in Fig. 1, and provide for the excitation of the make-alive electric discharge devices I03 and I05 in the proper sequence to feed the load 3I and to draw current from the load. as has been explained hereinabove.

When a hot-cathode electric discharge device I49 or I5I is energized, current is transmitted through it and through the make-alive electrode H9 or I2I of the corresponding make-alive electric discharge device I03 or I05. The make-alive electric discharge device is, therefore, energized and supplies power to the load 3| or draws current therefrom in the manner already outlined.

It is to be noted that the anodes I H and I45 of the hot-cathode electric discharge devices I49 and I5I are each connected to an anode I01 or I09 of the corresponding make-alive electric discharge device I03 or I05, while the principal circuits of the make-alive electric discharge devices are connected in shunt with the corresponding make-alive circuits including the hot-cathode electric discharge devices. When a make-alive electric discharge device is energized, therefore, the corresponding hot-cathode electric discharge device and its cooperative circuit is shunted out and deenerglzed. This feature of the system is similar to the feature discussed hereinabove and is important since, by utilizing it, a saving of considerable power may be effected.

It may aid to an understanding of the operation, to follow the circuits of the system shown in Fig. 4 in detail for one cycle of operation of the system. The hot-cathode electric discharge devices I49 and I5I are energized at the beginning or near the end of a half cycle of positive principal potential, depending on the relative disposition of the brushes 83 and 85, and the insulating inserts 41, 49, 5|, 53 and 55. Assume, for example, that the right-hand hot-cathode electric discharge device I5I is energized. Current is transmitted through a starting circuit extending from the right-hand terminal I3 of the secondary 1 of the transformer 5, through the principal circuit of the hot-cathode electric discharge device I5I, the make-alive electrode I2I of the righthand electric discharge device I05, the cathode I I3 of this discharge device, and the load 3|, and thence to the intermediate terminal I5 of the secondary of the transformer. When the current transmitted through the make-alive electrode I2I attains the proper magnitude, the right-hand electric discharge device I05 is energized, and current is transmitted between the principal electrodes I09 and H3 of the device and through the load 3|. The potential difference between the anode I09 and the cathode II3 of the right-hand electric discharge device I05 and, therefore, the potential difference between the anode I45 and the cathode I41 of the corresponding hot-cathode electric discharge device I5I is reduced to a small value and the latter device is deenergized. The same series of steps is repeated for the system on the left-hand side, and current is supplied to the load 3I from the power source and from the load to the power source in the manner explained hereinabove.

While hot cathode electric discharge devices of all types may be utilized in the system shown in Fig. 4, in practice I prefer tubes having the properties of the Westinghouse KU-62'7 or KU-628 grid-glow tubes.

In the system shown" in Fig. 5, the necessary variation in the grid or control potential is provided by phase shift circuits rather than by magnitude variation circuits. In this view the electric discharge devices I51 and I59 that are illustrated as supplying the load are shown in a symbolieal form representative of any device that might be utilized. In this system, as in the systems shown in the other-views, various types of electric discharge devices might be utilized, depending on the particular purpose for which the system is provided. Among the available electric discharge devices are gas-filled devices of the type having hot cathodes or vaporizable reconstructing cathodes (such as cathodes of mercury, tin or of alkali metals), gas-filled devices having cathodes of the'non-reconstructing type, and high vacuum devices of all types.

In the system shown in Fig. 5, the electric discharge devices I51 and I59 are connected to the secondary section 9 of the transformer 5 and to the load 3I in the same manner as the electric discharge devices 2| and 23 are connected in the system shown in Fig. l. The anodes I8I and I63 of the electric discharge devices I51 and I59 are connected to the terminals II and I3 of the secondary section 9, while the cathodes I and I61 are connected to each other and their junction point 29 is connected to the center tap I5 of the section 9 through the load 3I.

The control electrodes I69 and HI of the devices I51 and I59 are not supplied with potential through contactor elements such as the elements of the system shown in Fig. l but are coupled to a plurality of similar phase-shift circuits or networks I13 and I15.

Each of the phase shift circuits I13 and I15 comprises a transformer secondary section I11 and I19 provided with an intermediate tap IN and I83 which is' connected to a control electrode I69 and III of the respective electric discharge devices I51 and I59, through suitable grid resistors I85 and I81. A network comprising an inductor I89 and I9I and a resistor I93 and I connected in series with the inductor, is connected to the terminal taps of each section I11 and I19 of the secondary 1. The junction point I91 and I99 of each of the sets of resistors I93 and I95 and inductor I89 and I9I is connected to the terminals of a resistor 20I which has an intermediate tap 203 connected to the common junction point 29 of the cathodes I95 and I81.

The resistor 20I last-mentioned is capable of discharge devices being alternately connected to and disconnected from an additional section 205 of the secondary "I of the transformer 5, through a commutator 291 provided with an insulating segment 299 and a conducting segment 2I,I,-the commutator being rotated 'by the synchronous motor 31. When the resistor 2M is connected to the transformer section 295, it is connected directly across the section.

When the resistor 20I is disconnected from the secondary section 205, the potential supplied between each controlelectrode IE9 or HI and its associated cathode I55 or IE1 is determined solely by the phase shift circuits I19 or I15, respectively, and by the relationship of the magnitudes of the resistors I93 and I95 and the inductors I99 and I9I of the circuits. However, when the resistor 29I and the. transformer-section 205 are connected to each other, the control potential of the electric discharge device is varied by the application of the potential output of the section 295. Figs. 6 and 7-illustrate, vectorially and graphically, respectively, the condition of the electric I51 and I59 when the resistor "I is disconnected from the secondary section In Fig. 6, the principal potentials impressed on the electric discharge devices I51 and I59 are represented by horizontal vectors 2I3 and 2I5. The potentials impressed between the control electrode and the cathode of the electric discharge devices. when the section 205 is disconnected from the system, are substantially the potentials impressed between the opposite points III, I91 and I93, I99 of the phase shift networks I19 and I15, and are represented by oblique vectors-2I1 and 2I9. The vectors 2I1 and 2I9 lag in phase behind the corresponding horizontal vectors 2|! and 2I5 by considerable angles predetermined by the relationship of the impedances in each of the circuits I19 and I15. The phases of the principal potentials 2I9 and 2I5 applied to the two electric discharge devices I51 and I59 are maintained exactly opposite to each other, and hence the control-potential -vectors 2I1 and 2I9'are necessarily colinear, being equal and opposite, since the networks I13 and I15 are alike. -The actual condition which results in either of the electric discharge devices when the vectorial relationship is as shown in Fig. 6 is illustrated in Fig. 7. 1

In Fig. 7, the principal potential supplied to the two electric discharge devices I51 and I59 is represented as a sine curve 22I, plotted against time. The portion of the curve above theaxes of abscissae may be regarded as the positiveprincipal potential applied to one device I51, say, while the portion of' the curve below the axes of abscissae may be regarded as the corresponding positive principal potential applied to the other electric discharge device I59. The limiting control-potential curve corresponding to the positive principal potential impressed on one electric discharge device I51 is shown as a broken-line curve 223 intersecting the positive principal-potential half-waves. While. the limiting controlpotential curve is shown only for once! the electric discharge devices, it is apparent that a similar curve may be drawn for the other electric discharge device I59. The control potential is represented as a sine curve 225 shifted in phase with respect to the principal-potential curve by a considerable angle.' The control-potential curve 225 intersects the limiting control-potential curve 229 near the ends of the positive half-waves of the allel to the corresponding vectors of Fig.

7 considerable magnitude.

across the resistor 20 I an additional in-phase po- 1 tential is superimposed on each of the potentials provided by the phase-shifting circuits I13 and I15. This situation is represented vectorially in' Fig. 8 and graphically in Fig. 9.

In Fig. 8, the principal potentials applied to the electric discharge devices are represented by the opposite colinear vectors 2I9 and 2I5. The potentials applied-to the control electrodes when the secondary section of the transformer is not connected in the system are represented by a plurality of broken-line vectors 2I1 and M9 par- 6. The potentials superimposed by the secondary section 205 are represented by a plurality of broken-line vectors'221 and 229 parallel to and in the direction of the corresponding principal-potential vectors 2I9 and 2I5. The total potentials impressed on the control circuits of the respective electric discharge devices I51 and I59 are, therefore, represented by the sums of the two sets of vectors 2 I 1 and 221 and 2I9 and 229 and, therefore, by the vectors RI and 233 which lag in phase behind the principal-potential vectors 2I3 and 2I5, respectively. by an angle that is considerably smaller than the phase angles of the vectors 2I1 and H9.

In the corresponding graphic diagram shown in Fig. 9, the control-potential curve is now shown at 295, intersecting. the limiting controlpotential curve 222 at points near the beginnings of the positive half-waves of the principal-potential curve HI, and the current transmitted through the electric dischargedevices I51 and I59 from the power source is correspondingly of As the commutator 291 is rotatedfthe control system varies from a condition corresponding to Fig. 8 and Fig. 9 to a condition corresponding to Fig. 6 and Fig. 7, and current is alternately supplied to the load 3| and drawn from the load in a manner corresponding to that discused hereinabove in connection with the systems shown in Figs. 1, 3 and 4. It is to be noted that if the curves shown in Fig. 9 and Fig. ,7 are placed enc to end, the resulting curve will correspond to th: curve shown in Fig. 2. As long as the system i: in the condition represented in Fig. 9, power t supplied to the load 3| through the electric discharge devices I51 and I59. However, when thl system is reverted to a'condition such as is show] in Fig. I, any power that is stored in the induc tance of the load 9| is drawn therefrom and 181 back into the power source through the electri discharge devices I51 and I59.

In the systemshown in Fig. 10, the object o my invention is accomplished without the us of movable commutators or contactors. In thi system the variation in control potential is at tained by utilizing a timing circuit 299 or th type that is described in detail in a copendin application Serial No. 650,517 flied January I 1933 by William W. Viebahn and assigned to-tlt Westinghouse Electric 8: Manufacturing Corr P y.

In the system shown in Fig. 10, the electric di: charge devices I51 and I59 through which t1 load 3I is energized are connected to the load and to a secondary section 9 of the transformer 5 in the same manner as the corresponding devices oi! the systems shown in Figs. 1, 3, 4 and 5. That is to say, the anodes I6I and I63 of. the electric discharge devices are connected to the terminals II and I3 01 the secondary section 9 while the cathodes I65 and I61 are connected together and their junction point 29 is connected to the intermediate tap I5 of the secondary section through the load 3i. Potential is supplied between the control electrodes I69 and HI and the associated cathodes I65 and I61 principally by a phase-shifting circuit 231 of the type incorporated in the system shown in Fig. 5. One output terminal 239 of the phase-shift circuit 231 is connected to the controlelectrode I69 of one of the electric discharge devices I51 through,the usual grid resistor I65 and the other output terminal 24I oi the circuit is connected to the control electrode "I or the other electric discharge device I59 through the resistor I61.

A resistor 243 of suitable magnitude is connected between the control electrodes I69 and HI oi the electric discharge devices I51 and I59. The varying potential is intermittently supplied from the timing circuit 236, the output leads 245 of which are connected between the junction point 29 of the cathodes I65 and I61 of the electric discharge devices I51 and I59 and an intermediate tap 241 of the resistor 243.connected between the control electrodes.

The timing circuit 236 comprises a plurality of electric discharge devices 249 and 25I which may be 01' the type utilized in the other portion of the system or may be hot-cathode gas-filled electric discharge devices, hot-cathode highvacuum electric discharge deyices, or any other suitable devices. However, it' is to be noted that preferably the electric discharge devices 249 and 25I should be of the gas-filled type and should have an abrupt characteristic similar to the characteristicoi the other electric discharge devices utilized in the system.

' The anodes 253 and 255 of the electric discharge devices 249 and 25I are connected to the terminal taps 251 and 259 of a secondary 26I 01 a transformer 263, the primary 265 of which is supplied with power from the bus lines I. The cathodes 261 and 269 of the devices are connectedto each other and their junction point 21I is connected to the intermediate tap 213 of the secondary 26I through a potentiometer 215. The output leads 245 of the timing circuit 236 are connected to a movable tap 211 of the potentiometer 215 and to the central tap 213 of the secondary 26 I When either of the electric discharge devices 249 or 25I in the timing circuit 236 is energized, current is transmitted through the potentiometer 215 and a potential is impressed between the control electrodes I69 and HI and the cathodes I and I61 of the electric discharge devices I51 and I59.

The common junction point 21I or the oathodes 261 and 269 of the electric discharge devices 249 and 25I in the timing circuit 236 is connected to the lower or positive p ates 219 and 26I of a plurality oi. biasing-potential capacitors 263 and 265 while an additional intermediate tap 261 of the potentiometer 215 is connected to the upper or negative plates 269 and 29I of the capacitors through a plurality oi resistors 293 and 295. One of these resistors 293 is connected between one capacitor 263 and the movable tap 261 while the other of the resistors 295 is connected between 309 that is energized from the bus lines I. The.

terminal taps 3H and 3I3 of the secondary 301 are connected to the control electrodes 3I5 and 3I1 of the electric discharge devices 249 and 25I.

The timing feature or the circuit 236 is dependent on the relationship between the biasingpotential capacitors 263 and 295 and the resistors 293 and 295. The operation of the system is described in detail in the above-mentioned Viebahn application. However, it may be explained shortly here.

Assume for the purpose of the present explanation that the biasing-potential capacitors 263 and 265 are substantially in uncharged condition. The control potential supplied to the electric discharge devices 246 and 25I by the biasing potentiometer 30I and the transformersecondary 301 is not sufficiently negative to block the energization of either one of the electric discharge devices. Assume then that the principal potential on the right-hand electric discharge device 25I is positive. In such a case the right-hand electric discharge device is energized and current is transmitted through the potentiometer 215. By reason of the current thus transmitted, a difference of potential is impressed between the output leads 245 of the timing system. When the principal potential changes in polarity and the left-hand electric discharge device 249 has positive principal potential impressed thereon it is energized and the supply of current to the potentiometer continues.

As the timing-circuit electric discharge devices 249 and 25I are energized. a potential difterence exists between the common cathode terminal 21I and the movable tap 261 of the potentiometer 215. The biasing-potential capacitors 263 and 265 are, therefore, charged, the lower plates 219 and 26I accumulating a positive charge while the upper plates 269 and 29I accumulate a negative charge.

The left-hand capacitor 263 is moreover charged to a greater potential than the righthand capacitor 265 since the resistance in series with the former is less than the resistance in series with the latter.

As the electric discharge devices 249 and 25I continue to supply current to the potentiometer 215, a negative potential is superimposed on the biasing potential and the alternating potential that are impressed between the control electrodes 3I5 and 3I1 and the cathodes 261 and 269 of the timer-circuit electric discharge devices 249 and 25I, through the biasing potentiometer 30I and the secondary 301 of the transformer 309, respectively. When the negative potential attains a proper value, the electric discharge devices 249 and 25I are deenergized and the supply of current to the'potentiometer 215 ceases. The capacitors 263 and 265 are then discharged through the resistors 293 and 295 and the potentiometer 215. The control potentials impressed on the electric discharge devices 249 and 25I eventually attain such values that the electric discharge devices are again energized. This series of operations is repeated continuously as long as power is applied to the system.

Although certain of the elements such as the biasing potential and the alternating potential supplied to the control circuits of the timing electric discharge system 236 do not concern the present invention and are explained in detail in the above-mentioned Viebahn application, a word might be said about them here.

Two biasing-potential capacitors 293 and 285 are utilized instead of one, in order to extend the periods during which the electric discharge devices 249 and 25I are deenergized and energized. It is to be noted that the right-hand capacitor 265, which is connected to the control electrodes 3I5 and 3I1, determines when the control electrodes will attain negative potentials of such magnitude as to interrupt the discharging condition of the electric discharge devices. The left-hand capacitor 283, however, is maintained at a higher potential difierence than the right-hand capacitor 295 and maintains the latter in charged condition for an interval after the charging potential has been removed. Consequently, when the electric discharge devices are deenergized, the right-hand capacitor 285 is not at once discharged to produce a re-energized condition in the electric discharge devices 249 and 25I but remains in charged condition for an interval dependent on the magnitudes of the other elements in the system.

The biasing potential of the potentiometer 3M is provided in the timing system for the purpose of extending its range. The alternating potential applied by the secondary 301 of the transformer 309 is in opposite phase to the altemating principal potential supplied to the electric discharge devices 249 and 25I and is provided for the purpose of increasing the sharpness oi. the variation in the conditions of the timing system 236.

The operation of the system is illustrated in the vectorial diagram of Fig. 11 and the graph of Fig. 12. When the electric discharge devices 249 and 25I of the timing circuit 236' are deenergized the junction point 29 and the intermediate tap 241 are substantially at the same potential and the phase-shift circuit 231 determines the potential relationship of the electric discharge devices I 51 and I 59 in the power supply system and the principal potential is related to the control potential in accordance with the vector diagram of Fig. 11.

In Fig. 11, the principal potentials on the two electric discharge devices are represented as opposite colinear horizontal vectors 3I9 and 32I, while the control potentials are represented by oblique vectors 323 and 325 that are also colinear. The latter vectors 323 and 325 lag in phase behind the principal potential vectors 3I9 and HI by a large angle.

In Fig. 12 the principal potential which is supplied to the two electric discharge devices I51 and I59 is represented by a full-line sine wave 321. The control potential when the timing circuit 236 is deenergized is represented by a broken-line curve 329 which is a substantial angle out of phase with the principal potential curve. To simplify matters, it may be assumed that the limiting control potential curve of the two main electric discharge devices I51 and I59 is the axis of abscissae 33I.

It will be noted that. in the case represented by the curves 321 and 329, when the timing circuit 236 'is deenergized, the electric discharge devices I 51 and I59 become energized near the ends of the positive half-cycles of principal potential supplied thereto. Moreover, in the system shown in Fig. 10, the control electrodes I69 and HI of the electric discharge devices I51 and I 59 are connected to opposite terminals 239 and 2 of the phase-shift circuit 231. Consequently, the two electrodes are always in opposite phase to each other, and the control potentials 323 and 325 applied to the respective electric discharge devices I51 and I59 are related to the respective principal potentials 3I9 and 32I as shown in Fig. 11. When the timing circuit is deenergized, therefore, the electric discharge devices I51 and I59 are energized substantially at the ends of each of a series of successive half cycles.

When the electric discharge devices 249 and 25I of the timing circuit are energized, half-wave pulses of current are transmitted through the potentiometer 215 and the corresponding potentials are impressed between the-intermediate tap 241 of the resistor 243 connected to the control electrodes I69 and HI of the electric discharge devices I51 and I59 and the junction point 29 of their cathodes I65 and I61. These half-waves are substantially in phase with the corresponding half-waves of the principal potential applied to the electric discharge devices I51 and I59 and may be represented by a series of half-wave curves 333, as in Fig. 12. The net control potential impressed on the'electric discharge devices I51 and I59 through which the load 3I is energized may be represented by a curve 335 equal to the sum of the control potential 329 supplied by the phase-shift circuit 231 and the potential 333 supplied by the timing circuit 236. It is to be noted that this control-potential curve 335 either intersects the axis 33I of abscissae very near to the beginnings of the half-waves oi principal potential or lies above the axis 33I nearly up to the various points at which the principal potential changes. Accordingly, when the tim-- ing circuit 236 is energized, the electric discharge devices I51 and I59 whereby power is supplied to the load 3| are both, at first, energized substantially at the beginnings of the positive half-cycles of principal potential supplied to them.

Since the condition of the timing circuit 236 varies intermittently, the electric discharge devices whereby the load 3| is energized. will be intermittently energized for a number of positive half cycles at or near the beginning of each of the half cycles and then for a-second succession of haltcycles at or near the end of each half cycle. The power source will, therefore, supply energy to the load during the first set of intervals when the timing circuit is energized and will draw energy from the load during the second set of intervals when the timing circuit is deenergized.

I have shown and described in the present application a number of different modifications. My invention is, therefore, not to be restricted to any particular modification, nor is it. to be restricted to a system in which a particular type of electric discharge device is utilized. It is to be noted first that while independent electric dis-' charge devices have been illustrated herein as supplying half pulses of current to the load and as drawing half wave pulses of current from the load. such independent devices need not necessarily be utilized. Electric discharge devices in which a common cathode and a plurality of anodes are incorporated are well known in the art and such devices may be utilized in lieu of the devices shown herein. The same principle applies to electric discharge devices having a plurality of cathodes and a common anode.

Moreover, it should be noted that the timing circuit of the system shown in Fig. 10 inlieu of being applied with electric discharge devices of the control electrode type may be applied to a system of the type shown in Fig. 3 or Fig. 5, in which make-alive electric discharge devices are incorporated. In this system the timing circuit will, of course, replace the rotary switch system.

Again, it is well to note that the phase shift system of the type shown in Fig. 5 may replace either of the systems shown in the other views. In all cases where the make alive electric discharge devices are utilized instead of the control electrode electric discharge devices, the operation of the system depends on a current supply to the electric discharge devices rather than on potential variations. However, the current in the absence of phase shifting impedances varies in accordance with the potential and no diiiiculties are involved in replacing one type of electric discharge device by another.

Finally, attention is called to the fact that my invention should not be restricted to apply only in the limited scope of an improvement of the system shown in my earlier patent. Essentially, my invention is directed to a system for converting power of one frequency into power of another frequency. If instead of the pulsating current that is obtained in the systems described hereinabove, alternating current of the lower frequency is desired, a simple system for attaining this purpose may be provided in accordance with my invention. A system of this type is illustrated in Fig. 13.

In such apparatus, two similar systems of the type described hereinabove are provided. For the purpose of illustration two systems. such as are shown in Fig. 1, may be'utilized. The load; 3| of the two systems are replaced by the primaries 401 and 403 of a common transformer 405 having a single secondary 401, and the systems are so connected that the supply of pulses to one load or primary, say I, is of opposite polarity to the supply of pulses to the other load or primary, say 403. The contactors 33 and 35 or H5 and H1 or the timing circuits 236 of the systems whereby the loads are supplied are replaced by contactors 409 and 4 of such character that after a pulse is supplied to one primary, say 40!, no further current is supplied to it for the period of time during which the pulse is supplied and during this interval a pulse is supplied to the other primary say 403, that is of opposite polarity to the pulse supplied to the first primary. Accordingly, in the secondary 401 of the transformer 405, a current will be induced by the periodicity of the pulses.

It is to be noted that more than two systems such as are described hereinabove may also be utilized to feed the primaries of a common transformer. In such a case, the currents supplied to the individual primaries bear a predetermined phase relationship to each other and plural phase power is supplied by the secondary of the transformer.

Although I have shown and described certain specific embodiments of my invention, I am fully aware that many modifications thereof are possible. My invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and by the spirit of the appended claims.

I claim as my invention:

1. Apparatus for supplying periodic power of a given frequency to a load of the type having the property of storing a portion of the energy supplied thereto comprising a periodic power-supply source of a higher frequency than said given frequency, at least one electric discharge device incorporating means to be energized for initiating -a discharge therein, means for coupling said electric discharge device between said load and said source, means for energizing said initiating means during a cycle of said given frequency at a first predetermined point in said cycle, said energizing means operating to energize said initiating means at an instant bearing a predetermined phase relationship to the cycles of said higher frequency. and additional means for energizing said initiating means during the course of sa d cycle of said given frequency at a second predetermined point in said cycle, said additional energizing means operating to make the phase of said second predetermined point relative to the cycles of sa d higher frequency different from the phase of said first point.

2. Apparatus according to claim 1 characterized by that the phase displacement between the first predetermined paint and the second predetermined point relative to the cycles of the higher frequency is of the order of 3. Apparatus for supplying power to a load comprising a periodic power source, a first pair of discharge devices connected to said load, each of said discharge devices having a control electrode and a plurality of principal electrodes, means for impressing principal potentials on said discharge devices from said source, means for impressing control potential on said discharge devices to energize said discharge devices substantially at the beginnings of a plurality of successive periods of said source thereby to increase the current in said load to a predetermined value, said first pair of discharge devices being so connected to said load that the current supplied therethrough to the load is of a predetermined polarity, means for thereafter impressing control potential on said discharge devices to energize said discharge devices substantially at ends of a plurality of successive periods of said source thereby to decrease the current in said load to a predetermined value, a second pair of discharge devices connected to said load, each of the last said discharge devices having a control electrode and a plurality of principal electrodes, means for impressing principal potentials on the last said discharge devices from said source, means for impressing control potentials on the last said discharge devices to energize said discharge devices substantially at the beginnings of a plurality of successive periods, thereby to increase the current in said load to a predetermined value, said last pair of discharge devices being so connected to said load that the current supplied therethrough is of opposite polarity to the current supplied through said first pair of discharge devices, and means for thereafter energizing said second pair of discharge devices substantially at the ends of a plurality of successive half-cycles to decrease the current in said load.

4. Apparatus for supplying power to a load comprising a periodic power source, a first electric discharge means connected to said load. means for impressing potential on said first discharge means from said source, means for energizing said first discharge means substantially at the beginnings of a plurality of successive periods of said source thereby to increase the current in said load to a predetermined value,

said first discharge means being so connected to said load that the current supplied therethrough to the load is of a predetermined polarity, means for thereafter energizing said first discharge means substantially at ends of a plurality of successive periods of said source thereby to decrease the current in said load to a predetermined value, a second discharge means connected to said load, means for impressing potential on said second discharge means from said source, means for energizing said second discharge means substantially at the beginnings of a plurality of successive periods, thereby to increase the current in said load to a-predetermined value, said second discharge means being so connected to said load that the current supplied therethrough is of opposite polarity to the current supplied through said first discharge means, and means for thereafter energizing said second discharge means substantially at the ends of a plurality of successive half-cycles to decrease the current in said load.

5. Apparatus according to claim 4 characterized by means for maintaining the second discharge means deenergized during the whole interval of time during which the first discharge means is energized and means for maintaining the first discharge means deenergized during the whole interval of time during which the second discharge means is energized.

6. Apparatus according to claim 4 characterlzed by that the first and second means are energized as set forth periodically.

7. Apparatus according to claim 4 characterized by that the first and second means are energized as set forth periodically, the energization of the second discharge means being out of phase with the first discharge means.

8. Apparatus according to claim 4 characterized by that the first and second means are energized as set forth periodically, the energization of the second discharge means being in opposite phase to the first discharge means.

9. Apparatus according to claim 4 characterized by that the connection between the load and the discharge means includes a transformer having a secondary and a plurality of primaries, one of the primaries being supplied with current of one polarity through the first discharge means and another with current of the opposite polarity through the second discharge means.

10. Apparatus for supplying power to a load comprising a periodic power source, a first electric discharge means connected to said load, means' for impressing potential on said first dis charge means from said source, means for energizing said first discharge means at a substantial fraction of the period from the ends of a plurality of successive periods of said source thereby to increase the current in said load to a predetermined value, said first discharge means being so connected to said load that the current supplied therethrough to the load is 01. a predetermined polarity, means for thereafter energizing said first discharge means substantially at ends of a plurality of successive periods of said source thereby to decrease the current in said load to a predetermined value, a second discharge means connected to said load, means for impressing potential on said second discharge means from said source, means for energizing said second discharge means at a substantial fraction .of the period from the ends of a plurality of successive periods, thereby to increase the current in said load to a predetermined value, said secaoeavsa type having the property of storing a portion of the energy supplied thereto, comprising a powersupply source, an electric discharge'device incorporating means to be energized for initiating a discharge therein, means for coupling said electric discharge device between said load and said 1 source, means for energizing said initiating means in such manner as to cause said discharge device to transmit power in'the form of a current of one polarity from said source to said load for a predetermined period of time, means for thereafter changing the condition of said dischargeinltiating means in such manner as to cause said discharge device to transmit power in the form of a current of the same polarity from said load to said source for a second period of time, whereby,

during the latter period of time, the energy stored in said load is fed back to said source through said discharge device, and means for preventing the supply of any considerable amount of power from said source to said load during said second period of time, another electric discharge device incorporating means to beenergized to initiate a discharge therein, means for coupling said lastnamed discharge device betweensald load and said source, means for energizing said initiating.

means in such manner as to cause said lastnamed discharge device to transmit power in the form of a current of opposite polarity to that transmitted by said first-named discharge device from said source to said load for a predetermined period of time, means for thereafter changing the condition of said discharge-initiating means in such manner as to cause said lastnamed discharge device to transmit power, in the form of a current, of the same polarity as that transferred by said last-mentioned discharge device from said source to said load, from said load to said source for a second period of time, whereby, during the latter period of time, the energy stored in said load is fed back to said source through said discharge device, and means for preventing. the supply of any considerable amount of power from said source to said load during said last-mentioned second period of time.

12. Apparatus accordlng'to claim 11 characterized by that the power transmitted through the first-mentioned discharge device is out of phase with the power transmitted through the last-mentioned discharge device.

13. Apparatus according to claim 11 characterlzed by that the power transmitted through the first-mentioned discharge device is in opposite phase to the power transmitted through the last-mentioned discharge device.

14. In combination a periodic power source, means for deriving a potential from said source which is out of phase with the potential of said source and means for periodically superimposing on said out-of-phase potential an additional potential in-phase with the potential of said source to periodically shift the phase of said outof-phase potential.

.15. In combination a periodic power source, means for deriving a potential from said source which is out of phase with the potential of said era source and means for periodically superimposing on said out-of-phase potential an additional potential out-of-phase with said first-named outoi-phase potential to periodically shift the phase of said out-oi-phase potential.

16. Apparatus according to claim 15 characterized by that the additional potential is derived from the source.

17. In combination an alternating power source having a plurality of terminal taps and an intermediate tap, a first discharge device having a plurality of principal electrodes and a control electrode, means for connecting said principal electrodes between one of said terminal taps and said intermediate tap, a second discharge device having a control electrode and a plurality of principal electrodes, means for connecting the principal electrodes of the second discharge de vice between another terminal tap and the intermediate tap of said source, a circuit supplied through both said discharge devices, said circuit including charge-storing means to be supplied with a charge when said discharge devices are energized, means for connecting said chargestoring means to the control electrodes of said discharge devices in such manner that their potential becomes more negative when said chargestoring means is charged.

18. Apparatus according to claim 17 charac; terized by an additional source for supplying -potential out of phase with the potential of said alternating source, means for deriving a potential corresponding to the current transmitted by the discharge devices and means for superimposing the potential on the potential of said additional source.

19. Apparatus according to claim 15 characterized by a plurality of terminals between which trode and a plurality of principal electrodes and means for connecting the terminals between the control electrode and a principal electrode of one of the discharge devices.

20. The method oi utilizing a plurality of controllable asymmetrically conducting electric discharge devices to transfer power between an alternating-current device operating at one frequency and an alternating-current device operating at another frequency lower than said one frequency, said first-named alternating-current device and said last-named alternating-current device each having, at times, electromotive forces capable of supplying power to the other; said method comprising the steps of, at times, so controlling said electric discharge devices that they become conducting suiliciently soon in their respective conducting half-cycles when the potential oi the first-named alternating-current device is higher than the potential oi the lastnamed alternating-current device so as to transter a predominant amount of power from said first-named alternating-current device to said last-named alternating-current device, each electric discharge device remaining conducting substantially until the resultant electromotive force thereacross becomes smaller than a critical minimum value, and, at other times-so controlling said electric discharge devices that they become conducting sufllciently late in said halt-cycles so that a predominant amount of power is transferred from said last-named alternating-current device to said first-named alternating-current device.

JOHN W. DAWSON. 

